Elishashvili V I
Biokhimiia. 1980 Jan;45(1):20-7.
Levansucrase of G. oxydans L-1 which catalyzes the synthesis of the polysaccharide levan from the fructofuranosyl residues of sucrose has been isolated from the culture fluid and purified by chromatography on hydroxyapatite and gel-filtration on Sephadex G-100. The molecular weight of levansucrase as measured by DS-Na polyacrylamide gel electrophoresis is about 58000. The enzyme contains 25.86% of acidic amino acids, 13.74% of basic amino acids and 12.77% of aromatic amino acids. No cystine or cysteine residues were detected in the acid hydrolysate. The UV-absorption spectrum of the purified protein has a maximum at 280 nm and a minimum at 254 nm. The kinetic data suggest that levansucrase catalyzes levan formation, sucrose hydrolysis and sucrose glycosyl-free glucose exchange reactions. The initial rates of liberation of labelled glucose and labelled fructose during transfructosylation have been determined. Low molecular weight levans accelerate the rate of the polysaccharide formation and increase the ratio of the formed levan to free fructose.
氧化葡萄糖杆菌L-1的果聚糖蔗糖酶可催化由蔗糖的呋喃果糖基残基合成多糖果聚糖，该酶已从培养液中分离出来，并通过羟基磷灰石层析和Sephadex G-100凝胶过滤进行纯化。通过十二烷基硫酸钠聚丙烯酰胺凝胶电泳测得果聚糖蔗糖酶的分子量约为58000。该酶含有25.86%的酸性氨基酸、13.74%的碱性氨基酸和12.77%的芳香族氨基酸。在酸水解产物中未检测到胱氨酸或半胱氨酸残基。纯化蛋白质的紫外吸收光谱在280nm处有最大值，在254nm处有最小值。动力学数据表明，果聚糖蔗糖酶催化果聚糖形成、蔗糖水解和蔗糖无糖基葡萄糖交换反应。已测定了转果糖基化过程中标记葡萄糖和标记果糖释放的初始速率。低分子量果聚糖加速了多糖的形成速率，并增加了形成的果聚糖与游离果糖的比例。
